November 14, 2008

Fossil Challenges View Of Homo Erectus

According to researchers, a wide-hipped Homo erectus fossil found in Ethiopia suggests that females of the pre-human species gave birth to developed babies with large heads.

The finding leads some researchers to believe that helpless babies came along late in human evolution.

"We could look at this pelvis and then, using a series of measurements, we can calculate ... how big the baby's head could be at birth," said Scott Simpson, a paleontologist at Case Western Reserve University.

Simpson says the size of the 1.2 million-year-old pelvis shows that early females had wider hips, and were capable of giving birth to babies with heads that were 30 percent larger than previously thought.

"What this means is the offspring were not as helpless as a modern human," he added.

"It is not coming out walking and talking. But it was probably capable of more advanced behavior at a younger age like grasping, like sitting up ... than we would see in a modern human."

Extended childhood is a human characteristic, and the process of caring for helpless babies may have contributed to the development of human culture.

Scientists believe Homo erectus arose in Africa 1.8 million years ago and migrated to Asia and Europe before becoming extinct nearly half a million years ago.

Researchers knew little about Homo erectus until "Turkana Boy," an adolescent H. erectus skeleton was found in 1984.

The skeleton's slim hips led scientists to believe the species gave birth to helpless babies like modern humans.

The near-complete pelvis from Ethiopia challenges the previously held beliefs.

"This H. erectus would have even wider hips (than modern women)," Simpson said.

A main difference between male and female humans is their hip width. Females have wider hips which makes them sway as they walk, while men have slimmer hips which allows them to run more efficiently.

"The reason women do have that sway is their hips are a little further apart," Simpson said.